1. Field of the Invention
This invention relates to a sealant applying apparatus and a sealant applying method for applying, when assembling a toner container removably mountable on an image forming apparatus such as an electrophotographic copying apparatus or an LBP (laser beam printer), a sealant to the joined surface of members forming the toner container, and a toner container for an image forming apparatus obtained by the use of the sealant applying method.
2. Related Background Art
In image forming apparatuses such as electrophotographic copying apparatuses and LBPs (laser beam printers), there is known a cartridge directed to the facilitation of the replacement of process portions due to the termination of their service life, and the stabilization and improvement of the quality of printing, by including the process portions necessary for image formation integrally in a frame member, and making this frame member interchangeable.
FIG. 9 of the accompanying drawings is a cross-sectional view showing an example of the cartridge according to the prior art, and FIG. 10 of the accompanying drawings is a cross-sectional view showing the cartridge of FIG. 9 as it is separated into an upper frame member and a lower frame member.
The cartridge 1 shown in FIG. 9 is a toner container (hereinafter referred to as a "toner cartridge") removably mountable with respect to an image forming apparatus, and in a cartridge frame member 1a, there are disposed a photosensitive drum 2 as an image bearing member, and a cleaning device 3, a developing device 4 and a charger 5 as process portions disposed around the photosensitive drum.
The cleaning device 3 is comprised of a cleaning blade 3a for removing waste toner (waste developer) from the photosensitive drum 2, a scraping sheet 3b for preventing the removed waste toner from leaking outwardly, and a waste toner containing portion 3c for storing the waste toner therein.
The developing device 4 is comprised of a developing sleeve 4a rotatable in a predetermined direction to supply toner (developer) retained on the outer peripheral portion thereof to the photosensitive drum 2, a regulating blade 4b for regulating the layer thickness of the toner on the developing sleeve 4a, and a toner containing portion 4c for storing the toner therein and supplying it to the developing sleeve 4a.
The toner containing portion 4c and the waste toner containing portion 3c are formed in the cartridge 1 by an upper frame member A and a lower frame member B being coupled together by pawls 50 and screws 51, as shown in FIG. 10. The toner containing portion 4c is formed by the upper frame member A and the lower frame member B being coupled together, and a blade holder 30a holding the regulating blade 4b and the upper frame member A being coupled together, and prevents the leakage of the toner from the coupled portions by a seal member 14b being provided on the coupled portion of the upper frame member A and the lower frame member B and a seal member 14a being provided on the coupled portion of the blade holder 30a holding the regulating blade 4b and the upper frame member A. Also, the waste toner containing portion 3c is formed by the upper frame member A and the lower frame member B being coupled together, and a blade holder 30b holding the cleaning blade 3a and the upper frame member A being coupled together, and prevents the leakage of the toner from the coupled portions by a seal member 13b being provided on the coupled portion of the upper frame member A and the lower frame member B and a seal member 13a being provided on the coupled portion of the blade holder 30b holding the cleaning blade 3a and the upper frame member A.
As the seal members 13a, 13b, 14a and 14b in the toner cartridge as described above, use has been made of a flexible urethane foam sticked on the coupled surface of one of the upper and lower frame members by means of a both-side tape. However, if such seal members are adopted, it will be difficult to detach the flexible urethane foam and the both-side tape when the toner cartridge is to be disassembled and cleaned, and an inconvenience will arise in the process of sensing the toner cartridge. Therefore, an attempt is conceived to apply a sealant composed of foamed urethane to the joined surface and solidify it, instead of using the sealing members provided by the flexible urethane foam and the both-side tape.
On the other hand, the sealant applying apparatus according to the prior art for applying a sealant onto the coupled surface of one of the upper and lower frame members forming the cartridge is designed such that the upper frame member or the lower frame member of the cartridge as a workpiece is fixed by fixing means with the joined surface which is a surface to which the sealant is to be applied turned upwardly and a discharge nozzle for discharging the sealant by a predetermined amount is moved by a robot along the surface to which the sealant is to be applied, to thereby apply the sealant thereto. Also, a controller for controlling the movement of the nozzle has sequentially controlled the movement of the nozzle to a given target position [X, Y, Z] on real time while finding the data of a command position by a control function comprising PX=f(X, t), PY=f(Y, t) and PZ=f(Z, t) at each servo period (e.g. 5 ms) controlled by a timer.
However, the above-described prior-art sealant applying apparatus, which is designed such that the work is fixed and the nozzle for discharging the sealant by a predetermined amount is moved by the robot along the surface to which the sealant is to be applied, to thereby apply the sealant, has suffered from the following problems:
(1) When the weight of the apparatus for discharging the sealant is as great as about 30 kg, the carrying weight of the robot is also required to be of the same degree. Therefore, a large robot is required.
(2) By the discharge nozzle being moved, the liquid surface of the sealant in the discharge nozzle is vibrated. Therefore, the liquid surface is not stable and the amount of discharge is varied.
(3) When the discharge nozzle is moved to apply the sealant to a curved portion, the discharged liquid is greatly deflected outwardly by the influence of a centrifugal force and a desired locus cannot be described.
Also, the controller for moving the nozzle sequentially moves the nozzle on the basis of a given target position while finding a command position by a predetermined control function at each certain servo period, and this has led to the following problems:
(4) To stabilize the movement velocity of the nozzle to the target position, it is necessary to rapidly produce each command position data on the locus. This requires the controller to have a rapid calculating process capability.
(5) The controller is designed to output command positions in succession when the calculating process by the predetermined control function at each certain period is completed and therefore, if the calculating process time fluctuates, the output interval between the command positions will fluctuate. Therefore, the movement velocity of the nozzle is not stable and the amount of application becomes unstable. For example, when the sealant is applied to a series of surfaces comprising straight portions and curved portions to which the sealant is to be applied, the calculation time becomes long for the curved portions and therefore, the output interval between the command positions becomes long and the movement velocity of the nozzle is reduced. Thus, the amount of application to the curved portions becomes great and the locus becomes thick.
FIG. 11 of the accompanying drawings shows the manner in which the sealant is applied to the coupled surface of the upper frame member A shown in FIG. 10.
In the prior-art sealant applying apparatus, when a nozzle 52 is moved along a complicated application course 53 as shown in FIG. 11, the sealant sometimes deviates from the application course on the joined surfaces which are curved portions, due to the problems noted above, and when the sealant deviates from the surfaces 102a and 102b of the upper frame member A to which the sealant is to be applied, the prevention of the toner leakage by the seal member formed by the solidification of the sealant becomes insufficient when the upper frame member is coupled to the lower frame member B (see FIG. 10). Also, the thickness of the seal member is usually made greater than a predetermined gap after the coupling of the upper and flower frame members, and is set such that the sealant is crushed to fill up the predetermined gap completely, but if the amount of sealant applied to the joined surface which is the surface to which the sealant is to be applied becomes partly irregular, the thickness of the seal member formed on this joined surface by the solidification of the sealant will also become irregular and there will be created portions thinner than the predetermined gap after the coupling of the upper and lower frame members and thus, the toner may sometimes leak.